Ippo getting to be a second in a world class fight would open his eyes even more towards coming back. I can't really predict how the fight is going to go, but if Sendo beats Alf, imagine how that would light a fire in Ippo.
Also, Ippo needs to have the conversation with Kumi about her being suffocating with being anti-boxing. It's understandable that she's worried about the person she loves, but there's a fine line between being worried and being controlling. The story seems to be setting up the stage for that situation to explode when he decides to come back.
I forgot to mention that I'm here for do-rag Kimura
Honestly, this whole retirement arc has been a breath of fresh air. I love long term stories that spend hundreds of chapters on just the minute every day happening and thought process of these fighters. Ippo and OP for that matter are often falsely labeled as slow paced stories. There's a difference between slow pacing and long term stories.